package answer;

import java.util.Iterator;

public class ResizingArrayStack<Item> implements Iterable<Item> {
    private  int N = 0;
    private  Item[] a =(Item[]) new Object[1];

    public boolean isEmpty(){
        return N == 0;
    }
    public int size(){
        return N;
    }

    private void resize(int max){
        Item[] temp  =  (Item[]) new Object[max];
        for (int i = 0; i < N; i++) {
            temp[i] = a[i];
        }
        a = temp;
    }
    public void push(Item s){
        if(N == a.length)
            resize(2*a.length);
        a[N++] = s;
    }
    public Item pop(){
        Item item = a[--N];
        a[N] = null;
        if (N>0&&N == a.length/4)
            resize(a.length/2);
        return item;
    }
    @Override
    public Iterator<Item> iterator() {
        return null;
    }

    private class ReverseArrayIterator implements Iterator<Item>{

        private int i = N;
        @Override
        public boolean hasNext() {
            return i>0;
        }

        @Override
        public Item next() {
            return a[--i];
        }

        @Override
        public void remove() {

        }
    }
}
